Flow deviation and critical choking in transonic turbine cascades operating with non-ideal compressible flows

Flow deviation and critical choking in transonic turbine cascades operating with non-ideal compressible flows

Tosto, F. (TU Delft Flight Performance and Propulsion)
Giuffré, A. (TU Delft Flight Performance and Propulsion)
Colonna, Piero (TU Delft Flight Performance and Propulsion)
Pini, M. (TU Delft Flight Performance and Propulsion)

2022

In this work we examine the flow deviation and its relationship to critical choking, i.e., choking of the meridional component of velocity, in transonic turbine cascades operating with non-ideal compressible flows. To this purpose, a generalized expression of the corrected flow per unit area as a function of both the thermodynamic state and the molecular complexity of the working fluid, the Mach number, and the amount of swirl is derived. The trends of the corrected flow with respect to these quantities are used to infer physical insights on the flow deviation and on the operability of transonic turbine cascades in off-design conditions. Moreover, reduced-order models for the estimation of the flow deviation and the preliminary assessment of the losses have been developed and validated against the results of CFD simulations performed on a representative transonic turbine stator. Results suggest that flows of dense organic vapors exhibit larger deviations than those pertaining to compounds made of simple molecules, e.g., air. Furthermore, transonic turbines expanding dense vapors reach critical choking conditions at lower Mach numbers than the ones operating with simple molecules, and are affected by larger dissipation due to viscous mixing.

choking
flow deviation
loss breakdown
non-ideal compressible fluid dynamics
Organic Rankine cycle
turbine

http://resolver.tudelft.nl/uuid:4cf07844-47da-4036-89c9-9ad695bdad98

https://doi.org/10.33737/jgpps/151659

2515-3080

Journal of the Global Power and Propulsion Society, 6, 181-199

Institutional Repository

journal article

© 2022 F. Tosto, A. Giuffré, Piero Colonna, M. Pini